The invention relates to a method and a device for connecting the end of a flattened tube of plastic foil to the beginning of a subsequent tube, said tubes being used in particular for applying sleeves onto bottles or the like.
When using such a tube, it is drawn from a reel. When the end of the tube has been reached, this end has to be connected to the end of a tube being situated on a subsequent reel, to wit in such a way that the process of applying sleeves on subsequent bottles will not be interrupted.
Such a method and device are known from U.S. Pat. No. 3,473,994. According to this document, the beginning of the subsequent tube is put against the end of the spent tube and then fixed with adhesive tape. To that end, both ends should be positioned in relation to one another with extreme accuracy both in longitudinal direction and in transverse direction. This requires a complicated device, which is sensitive to malfunction. In case of inaccurate positioning, malfunctioning may also occur in the machine which is employed for applying the sleeves.
According to another method, the end of the tube from the spent reel can be stuck in the beginning of the tube on the next reel and be fixed with adhesive tape. This has the disadvantage that the inner diameter in reduced across the distance where the beginning of the next tube is stuck in the end or the tube of the spent reel. This can cause problems when applying the sleeves on a bottle with the help of the machine concerned.
Now the object of the invention is to provide a method in which these difficulties do not arise. This method is characterized by the following steps: the leading edge of the beginning of the flattened tube is provided with an obliquely cut-away corner at both longitudinal edges; the thus established two loose lips are separated from each other; the end of the spent tube is slid between the lips and fixed in relation to said lips.
It has turned out that such a method can easily be carried out. Neither does the method cause any difficulties in further processing of the tube on the machine by which sleeves are mounted on objects, even it parts of both tubes are on top of each other.
In particular it will be provided for, that the end edge of the spent tube is at a distance from those locations of the longitudinal edges of the subsequent tube where the obliquely cut-away corners of said tube end, thus leaving a free space between the longitudinal edges of both flattened tubes.
Through this, it is achieved that there is always an opening, be it a small one, at the point where the tubes are connected to one another, so that air possibly present in the tube is allowed to escape.
For fixing the ends of both tubes in relation to each other, adhesive tape or an xe2x80x9cimpulse sealxe2x80x9d can be used, in which the materials of said tubes are melted together by means of a short-time, pressurized supply of heat.
The invention also relates to a device for applying the method described above. Said device is characterized by: a frame in which some reels of flattened tube can be accomodated; means for supporting the beginnings of subsequent flattened tubes, said beginning being provided with obliquely cut-away corners near its longitudinal edges for forming loose lips; a guide, extending in parallel to said means for supporting the beginnings of the subsequent tubes, for supporting a transport module comprising a beak situated within said tube, which is kept in place by rollers mounted outside of said tube, and a tube transport motor drawing the tube across the beak; with further means being provided for bringing said transport module to a location where the beginning of a subsequent tube is situated and for bringing the end of a tube between the lips of said subsequent tube.
It is desirable that both leading edges of the lips of a subsequent tube are positioned exactly on a certain location.
In connection with that, means will be provided for, such as in the shape of clamping members, for clamping the beginning of a subsequent tube, at a distance from said lips, for the time during which said tube is not used.
It is desirable, that applying sleeves on the objects should not be interrupted on commencing use of a subsequent tube.
To that end, it will be provided for, that after commencing use of a subsequent tube, the transport motor will temporarily move it at a higher speed in order to create a buffer supply, which is used during connecting the end of one tube to the beginning of a subsequent tube.
For connecting the tubes to one another, the device will in particular be provided with sealing beams, which are carried by the transport module and are situated above and below said tube and which can be brought together and be heated for melting the abutting parts of the tubes together where a part of the beak is situated.
The presence of the beak prevents the tubes from being melted to each other internally as well, on account of which the tubes could no longer be pulled across the beak.
Given the relatively small dimensions of the lips of a tube kept in stock, a belt can be used for supporting the lips. This belt need only have a small thickness.
In order to guarantee, that the lips will be at the desired location when they has to be connected to the ends of a tube, the transport module will be provided with belt guides being connected to the belt guided across some rollers and being situated at both sides of the beak and extending to near its lateral edges.
Since a printed foil is used in most cases, it must be provided for that when cutting a sleeve from the tube, the print is situated at the proper position.
In connection with that, the transport module can be provided with a detecting photo cell which, on detection of a certain point of the print, will stop the tube transport motor, a cutting knife being present for cutting the tube in a certain position.
In view of this a cutting knife can be situated at each clamping member for clamping the beginning of a subsequent tube, and operation of the clamping member and the cutting knife can take place by means of a pressurized medium cylinder being located on the transport module.